Radar Phase Noise Reduction via Delay Function Nulls
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Solution Overview
Problem
Conventional radar systems suffer from significant phase noise interference, which degrades their sensitivity and signal-to-noise ratio, particularly in Doppler radar applications where phase noise is not uniformly distributed across the power spectral density.
Innovation Solution
The proposed solution involves modulating the received phase noise spectrum with periodic nulls using a two-way range delay function, strategically positioning these nulls to cancel specific portions of the phase noise spectrum, thereby reducing its impact on radar sensitivity. This is achieved by selecting appropriate pulse repetition frequencies or time delays in pulsed Doppler systems and time delays in continuous wave systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radar systems use standard phase noise filtering, then the system structure remains simple, but phase noise significantly degrades radar sensitivity and signal-to-noise ratio
Solution Approach 1:
The patent converts the harmful phase noise spectrum into a beneficial structure by using the two-way range delay function to modulate it with periodic nulls. The delay function, which originally just represents signal propagation time, is strategically used to create nulls that cancel phase noise at specific Doppler frequencies, thereby converting a harmful factor into a useful noise reduction mechanism
Solution Approach 2:
The patent changes the parameter of pulse repetition frequency (PRF) to strategically position the nulls of the delay function. By selecting specific PRF values, the system adjusts the spectral distribution of phase noise to align nulls with high-phase-noise regions, thereby reducing the overall impact of phase noise on radar sensitivity without requiring additional hardware
2Object-affected harmful factors
If the pulse repetition frequency is adjusted to position nulls for phase noise cancellation, then phase noise reduction is achieved, but the system requires precise frequency selection and coordination
Solution Approach 1:
The patent makes the two-way range delay function serve multiple purposes: it continues to represent the physical signal propagation delay while simultaneously acting as a spectral shaping function that creates nulls for phase noise cancellation. This multi-functionality eliminates the need for separate noise filtering hardware, as the existing delay mechanism is repurposed to perform both its original function and noise reduction
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The strategic placement of nulls in the phase noise spectrum effectively reduces the phase noise effect, enhancing the signal-to-noise ratio and improving the sensitivity of Doppler radar receivers, as demonstrated in various graphical representations and system configurations.
Implementation Method 1
the received phase noise spectrum is modulated with periodic nulls due to the two way range delay function
Implementation Method 2
strategically position the nulls of the delay function to cancel portions of phase noise spectrum
Implementation Method 3
Doppler radar identifies the velocity of an object by mixing the transmitted carrier with the wave reflected from the moving object and determining a small change in frequency
Implementation Method 4
mixing the transmitted carrier with the wave reflected from the moving object
Data Source
AI summary
Methods and systems that reduce the effect of phase noise in radar receivers. The received phase noise spectrum is modulated with periodic nulls due to the two way range delay function. The system and method include strategically positioning the nulls of the delay function to cancel portions of phase noise power spectral density, the portions of the power spectral density of the phase noise being selected so that effect of phase noise in radar sensitivity is reduced.